An Opinion on an Architecture

Doug Plata has a new website at with a concept for sustainable Lunar development. He sent me the link and suggested I look it over. I read it through the first time as a plan and promptly (in my mind) picked it apart. I went over it again as a conceptual approach coming away with considerably more positive feelings about it. I am quite opinionated about various approaches to getting things done with a normal reaction that I could do this or that better after someone else has done the heavy lifting of the initial approach. Anyone interested in developing the moon would benefit from a reading of his website including all the specific links.

My take on it is that it contains many desirable features and has missed a few critical points. One of the main ones is the knock on effect that the drop in launch prices will bring. I can see prices to LEO dropping to under $500.00 a kilogram within the timeframe he is suggesting. FH, New Glenn, BFR, etc in the near future. At that rate, a billion dollars launches 2,000 tons into LEO.  This is the main basis for the criticisms I see. I will use that number in this post.

Doug suggests that a small percentage of the NASA budget could implement his scenario. A billion a year being 6-7% of the normal budget would be sufficient if used intelligently, mostly with COTS type applications. I don’t see any NASA managed project of this magnitude being immune to the various congressional feature creeps for the long term. Major NASA programs  tend to multiples of that, which then tend to political rather than effectiveness direction. He makes a few mentions of international participation which to me has the same effect multiplied. IMO, his scenario needs to be a private venture ramrodded by a hardheaded businessman with a solid technical team in order to remain in reasonable cost territory.

I can see a variation of his vision being done possibly faster than his website suggests. One example is that of the partial gravity research that has been left fallow for so many decades. He suggests the partial gee research takes place on the moon after the early human landings. I suggest that a 50 ton partial gravity research facility in LEO will be possible for $25M in launch costs and  less than $10M in hardware costs. $200.00 a kilogram for hardware is in line with terrestrial computers and electronics, and well above most hardware. With low launch costs, much of the over engineering of current spacecraft can be eliminated. The partial gravity research could start year one with results starting to be well characterized before the first human landings on the Lunar surface. It could be known whether a fetus could develop at 1/6 gravity by the time the first couple headed that way. It may not even be necessary to have a centrifuge on the moon, or it may be desirable to have a much larger one. That knowledge is necessary and long overdue.

The focus on finding and mining water dominates much of Dougs’ concept. I think the results of inexpensive launch has not been well factored in. With methane/LOX a mass ratio of about 5 from LEO to the Lunar surface puts a ton in place for about $2.5M for launch costs.  A hundred tons of water for a quarter billion FOB moon seems like a good early supply. Four hundred tons of equipment and supplies delivered to the moon for a billion dollars seems like a good year two operation. By exploring and prospecting for all potential valuables instead of a water dedicated mining operation, it seems possible that better and easier sources of almost everything will be found. It would be most unfortunate if a massive effort were made to extract water from the polar regolith only to find that nearly pure sources were available in many locations. It would be bad as well to hope that better sources would be found only to find that the polar regolith was indeed the only reasonable source. I suggest a lot of exploration and prospecting before major mining investments.

Doug puts a lot of emphasis on communicating the excitement to Earth in as many languages as possible even if by naturalized Americans with all early crew members multilingual. I personally place less value in talking to people than getting them there in the first place. If a person can be delivered to the Lunar surface alive and healthy with a ton of gear, launch costs of $2.5M per person are down to the point that any interested nation should be able to pay their own way. The six person international teams that he suggests could get there, stay a while, and back for under $40M. Any nation group that can’t or won’t supply that level of support shouldn’t expect much sympathy from those that do pay. International pride would come from self sufficient groups paying their own way instead of being dependent on the charity/political connections of others.

The gymnastics and dance routines that he suggests be practiced with tethers on Earth could instead be developed and learned properly in the Lunar environment. Artists need some freedom to be artists. Earth control and choreography is unlikely to give the best results  compared to the experimentation on location by the artists themselves. Again, $40M for a gymnastics or dance troupe to spend a month or so on the moon seems a quite reasonable cost. It also doesn’t require your geologist to be selected for athletic abilities.

The suggestion is that crew should have very long stays of several years or perhaps indefinitely due to costs and transport risks. I suggest that that attitude is caused by the ridiculous prices of crew transport that exist now, and not those that will exist in the near future. At the $2.5M that I suggest will be possible to get someone to the Lunar surface, and about that much more for a year of supplies, crew rotations could resemble those of the ISS currently. While some could stay longer and would be encouraged to do so, I don’t see it being the bottleneck to Lunar development.

Some of the hardware in the scenario seems to be missing a few tricks. The lander based on the  Masten Space Systems work with ULA seems like a future manned transportation system to the Lunar surface. For early hardware delivery, a variation of the Falcon 9 hover slam seems to have something to offer. A stage that hits hard or tips over is not going to explode as seen in footage of some early barge landings. The propellant will evaporate in the vacuum faster than it could sustain ignition. So the cargo could be saved even in the early learning curve landings. An upright stage that landed properly could unload with an onboard gantry crane in the 1/6 gravity. Several companies could learn by doing rather than learn by designing and simulating and then learning the hard way anyway.

A Lunar rotovator has been proposed many times and a development scenario like Dougs’ could afford to learn to operate it. A 1,600 m/s rotovator could pick up as well as deliver which would eliminate much of the need for mining or delivering water. A 25 ton unit could pick up and deliver ton packages, though not people at first.  That would be about a $100M investment that would pay off in operational knowledge that could apply to LEO, Mars and asteroids just a few years on.

A depot scenario would benefit this development. A delivery to LEO that had extra mass capacity could deliver propellant as a secondary payload for nearly free. A refueled upper stage would make a dedicated transfer stage unnecessary. Refueling or off loading extra propellant in Lunar orbit could also make the trips more cost effective. Storage facilities in Lunar orbit and on the surface would definitely enhance the value of Lunar propellant when it did start becoming available.

Doug mentions saving the capability of the SLS for Mars missions. I say why bother if 4,000 tons can be placed in LEO for the price of one SLS launch. I also disagree that a manned Mars flyby is a useful mission. Phobos and Demos mission, maybe, though I’m not sold on those either. Of course, not being a Mars enthusiast, I probably would be a hard sell for a surface mission as well.

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I do construction for a living and aerospace as an occasional hobby. I am an inventor and a bit of an entrepreneur. I've been self employed since the 1980s and working in concrete since the 1970s. When I grow up, I want to work with rockets and spacecraft. I did a stupid rocket trick a few decades back and decided not to try another hot fire without adult supervision. Haven't located much of that as we are all big kids when working with our passions.

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About johnhare

I do construction for a living and aerospace as an occasional hobby. I am an inventor and a bit of an entrepreneur. I've been self employed since the 1980s and working in concrete since the 1970s. When I grow up, I want to work with rockets and spacecraft. I did a stupid rocket trick a few decades back and decided not to try another hot fire without adult supervision. Haven't located much of that as we are all big kids when working with our passions.
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17 Responses to An Opinion on an Architecture

  1. DougSpace says:

    John. Thanks for your willingness to review my site. Before I respond, I’m wondering what your thought are on the large inflatable habitat with a flat roof so that regolith shielding could be easily, telerobotically placed on top. Thanks.

  2. johnhare johnhare says:

    I hadn’t thought about that one that much. I’m still in the explore/prospect/decide/design mode myself. I think the large habitats would be year three at least giving time for some location specific requirements. Being in construction myself, I have seen a few one size fits all solutions that don’t. If large underground caverns are widely available for instance, the habitats may be inflated units that don’t require covering. The centrifuge may want to be larger and operate in the vacuum of the cavern, or not. Does anyone know if there are deep canyon like features that block radiation from most of the sky already?

    Mainly, I’m cautious about over planning before knowing the facts on the ground. Apollo is a cautionary tale for me symbolizing extreme focus at the expense of flexibility.

  3. DougSpace says:

    Large underground caverns are associated with lava flows such as the mare. They are not near the lunar poles where the extended sunlight and volatiles are. I was at the LEAG conference and there is general consensus that the poles are the right place to start. Covering a habitat with regolith is a pretty straightforward solution.

  4. Paul D. says:

    As transportation costs decline, lunar resource extraction’s focus would shift. Instead of getting bulk material like propellants to save on launch costs, the focus would be on materials that are rare on Earth. Following Dennis Wingo, I’m thinking of meteoritic metal in lunar regolith for platinum group elements.

    With this shift, lunar activities would involve prospecting for especially enriched zones (near lower speed impacts of high metal impactors, say) and demonstration of mining/processing equipment on the lunar surface.

  5. DougSpace says:

    Detailed response to John:

    My website’s subtitle indicates that its architecture is intended as a proposal for the current Administration. Musk’s ITS concept last year had no apparent impact on NASA’s plans for either the Moon or Mars. The same seems to be true with his BFR-BFS concepts. It is hard to blame the policy-makers for this because the BFR-BFS plans could change but more importantly, the BFR & BFS are not at a stage of hardware development to where it can, at this time, be incorporated into the space architecture during the current term of this Administration.

    If BFR-BFS reaches a level of demonstration where space architects can take it seriously then great! But until then, NASA will make plans with what is more certain and clear. My argument is that the FH is about as near-term as it gets — even well before the SLS maiden launch. When BFR become available, hooray, my architecture can easily switch out the launcher and the cost of lunar development comes down. But until the BFR reaches a level of demonstration that gives assurance of near-term reality, then the FH is the most cost-effective, capable launcher we’ll have. My architecture posits that a whole lot can be started with a FH-Xeus-based architecture. And with ISRU, most of the mission mass can be produced on the Moon in the near-term which, in effect, makes the FH even that more capable.

    Blue Origin itself indicates that only the first stage of the New Glenn will be reusable:
    Also, it would place only about 45 tonnes into LEO. So, it is not clear to me that it would deliver payload to LEO at a lower cost than the FH much less the $500/kg that John suggests. With the FH presumably being available before the NG, I prefer proposing a FH-based architecture. Besides, Bezos proposes only 5 tonnes of cargo and not crew to the Moon.

    > I don’t see any NASA managed project of this magnitude being immune to the various congressional feature creeps for the long term.

    John seems to confuse my proposal with NASA’s large, cost-plus contracting programs which nearly always are seriously over budget and suffer political direction changing. But COTS, Commercial Cargo, and Commercial Crew are what’s needed. These public-private programs intentionally limit NASA’s management and mission creep. They are also fixed-price contracts. The milestones are negotiated with the participating companies and over-budgets and schedule slippages are eaten by the companies. These COTS-like programs have been very successful. We should simply repeat this approach for a program to set up a near-term transportation to the Moon. I don’t think that that proposal is too much of a stretch. The COTS-like programs have grown in budgetary support, are quite stable across multiple administrations, and have had little (any?) direction changes.

    My proposal is definitely NOT like how we’ve done the ISS in which international involvement has arguably increased costs and slowed progress. The reason that I have only limited mention of international involvement is because I am proposing that the US have a Lunar COTS set of programs in which we develop an end-to-end US transportation system. The international involvement would be for us to openly call for any other nation to do likewise and fund their own companies to develop dissimilar, redundant elements of the transportation, telerobotic, & habitation systems with an eye towards setting up a competitive market place. Very, very different than the ISS. Please re-read my International Lunar COTS page to better understand what I am proposing.

    When do we need to know the artificial gravity prescription (AG Rx) for healthy gestation and childhood? No sooner than when we have a lunar population large enough and young enough to where this becomes an issue. It is, I think, potentially dangerous to suggest that we aren’t ready to go to the Moon until after we conduct AG Rx in LEO. If we give policy-makers any excuse to slow things down it will probably happen. We don’t need the AG Rx to get started developing a permanent lunar base. And, as we establish the lunar base, the AG Rxs would be a side project using the existing crew’s centrifuge. It’s not the cost of the LEO AG Rx that concerns me as much as the potential delay that it could introduce. Also, the gravity environment on the Moon is fundamentally different that the gravity environment of a rotating facility in LEO. We won’t know of the effect of the constant 1/6th gee vector combined with the rotating frame of reference until we do the studies on the Moon (or Mars).

    > The focus on finding and mining water dominates much of Dougs’ concept.

    To be clear, I do not place the harvesting of lunar polar ice as being on the critical path to either the Moon or Mars. That is to say, if the harvesting of lunar ice is for some reason too difficult (unlikely IMO) we would none-the-less still want to go to these destinations. But we should definitely still aim to harvest the water ice because then, what we launch from Earth would be more payload and less propellant.

    As an aside, I use the term “harvest” rather than “mining” because mining is generally associated with a large industrial process of crushing rock with heavy equipment. Extracting scattered water crystals from the fluffy regolith (that the LCROSS results indicate) uses very different equipment and processes than does terrestrial mining.

    > A hundred tons of water for a quarter billion FOB moon seems like a good early supply.

    Again, this assumes not the FH nor the NG but the BFR which is not a practical consideration for current policy-makers.

    > It would be most unfortunate if a massive effort were made to extract water from the polar regolith only to find that nearly pure sources were available in many locations.

    First of all, it wouldn’t be a “massive effort”. Harvesting enough icy regolith at Cabeus Crater concentrations to refuel the lander wouldn’t be a massive operation. I think it more likely than not that the very first lander could be fully refueled with the solar power and ice-harvesting telerobots that the lander itself brought. Also, whereas a plausible scenario could be made that ice harvested far from a so-called “Peak of Eternal Light” (PEL) and then hopped to the PEL for electrolysis, working with ices local to one of the PELs would be a logical place to start even if those concentrations were lower. If one were to invoke nuclear power as an alternate solution then we’re just introducing a complication which makes winning the policy argument that much harder.

    > I personally place less value in talking to people [in their languages] than getting them there in the first place.

    Irrelevant because these are not mutually exclusive. I’m not sure that John appreciates my argument for the historically significant aspect of establishing humanity’s first, off-Earth foothold. I could have made the case for 12 launches for a total of 72 crew. But future generations won’t be able to remember the 72 names or what each did or where they were from. Rather, I intentionally limit it to an initial crew of four, long-duration couples who are American but who are not exclusively English-speaking natives. It’s America, the land of immigrants, showing what free peoples are all about. Opening the space frontier to the rest of the world. Our companies selling transportation to national astronauts of many (probably all) of the nations of the world. As a policy argument, there is a lot for the current Administration and Congress to like. They want a space program “worthy of a great nation”. I think that my architectures would give them want the want in spades! Compared to the default plan (SLS, DSG, ISS-only partners) I think that my Plan gives far greater value while setting the stage for actual, private settlement.

    > International pride would come from self sufficient groups paying their own way instead of being dependent on the charity/political connections of others.

    I see that my International Lunar COTS page failed to mention that about 70% of the nations could afford to purchase access to the Moon from the commercial transportation system. I will revise that page to make it clear. The only charity that I see would be for a nation such as Tuvalu (population 12,000) who might need some help affording access to the Moon whatever the launch vehicle.

    > The gymnastics and dance routines…developed and learned properly in the Lunar environment.

    It makes straight-forward sense to make the most of the crew’s time on the Moon. I envision a weekly TV program from the Moon highlighting a remarkable show. It wouldn’t make sense to take crew’s time on the Moon figuring out a routine, piece of music, or whatnot. Figure out the programming on Earth, have it well practiced, and then, on the Moon, brush up the practice in the lunar environment and then perform it well for the world to watch. In the second year, yes, there could be a large, inflatable sports hab, concert hab, etc and highly skilled professionals could perform and experiment to their heartens desire.

    > …suggestion…crew…long stays…due to costs and transport risks.

    Every time we launch, land, ascend, and re-enter crew there is the risk of LOC. We can reduce that risk substantially by extending crew stay. We could also grow the population faster via extended crew stay. Even at BFR prices, crew transportation costs would be cut about in half if crew doubled their stay time. Return criteria using biomedical indicators should determine when crew return rather than an arbitrary rotation schedule.

    > The Masten [lander]…seems like a future manned transportation system…

    Umm, true. But it’s based upon the Centaur which is a well-established piece of hardware. With Lunar COTS-level funding, that should be able to be modified to be cargo lander I would expect within about the first term of the current Administration.

    > the Falcon 9 hover slam

    Yeah, I think that we should build a real, reusable lunar lander designed for that purpose. It’s hard to imagine a F9 hover slam-based architecture getting any traction from any quarters. Crashes during experimentation with hardware that’s not sustainable isn’t what the decision-makers are looking for.

    > Lunar rotovator

    Yeah, I don’t think that this one is going to get any traction either. Too uncertain at this point.

    John, I’m not talking about what is theoretically possible. I’m talking about an architecture that we can move forward with now.

    > A depot scenario…

    …would introduce a delay which is not what the current Administration is looking for. We can start with one-way, direct delivery of full-scale telerobots which could leverage their mass to produce a much greater mass of lunar-derived propellant. Landers / ferries can act as propellant depots during the initial phases with smart transportation architectures. For example, if we think creatively, two refueled landers, docking and pushing each other in cis-lunar space could achieve a great deal of capability. Stationary propellant depots could come later when they are actually needed.

    > Doug mentions saving the capability of the SLS for Mars missions.

    I would be all too happy replacing the SLS with a far more cost-effective BFR. Believe me. But the BFR is apparently failing to have any significant on national space policy planning. Why? We can argue that it’s constituently-driven politics. But another legitimate reason is that the BFR is not ready for prime time. Until it is, then I think that a FH-Xeus architecture for the Moon is something that we can do now. I am unaware of a credible FH-based Mars architecture. Until something better comes along, I don’t think that we’ll see the decision-makers move away from the SLS.

    In conclusion, I think that my architecture is a plausible, near-term proposal which leverages hardware we can develop soon. With the telerobotic phase, we can set the stage for crewed landings of great historic significance allowing America to lead in opening space to humanity. Please check out, consider joining the Space Development Network and I look forward to everyone’s feedback.

  6. johnhare johnhare says:

    I think our main point of disconnect is who runs the show. A government run operation, even with COTS, is significantly more expensive than what you are suggesting here. SpaceX and Boeing got contracts or $6.8B for crew capsules to go on nearly stock vehicles. Lunar COTS is not the answer though it would be better than the cost plus approach as you say.

    That leads to our second difference which is doing it during the term of this administration. I think this administration will have as little to do with effective settlement as the last one or the next one. In my view, the effects of any plan on the plans of the administration is doomed to serious problems. A distance from government control will be necessary to move forward, especially as fast as you would like. Ditto any international government involvement. There are foreign companies that could bring a lot to the table as long as they are not under the same constraints as NASA or ESA.

    The $500.00 a kilogram I suggest possible is very close to that suggested by a fully mature FH by many proponents. New Glen and BFR are going to have to beat this by some margin if they are to see commercial service. Both of them are possibly in service by the mid 2020s. Even at double that number though, it is possible to do some serious development as long as it is managed by people with a firm eye on the bottom line, and the top line.

    The early artificial gravity research I suggest in LEO would in no way interfere with Lunar development if that is the goal. The relatively minor costs would accelerate knowledge of the possible before the first possible landings, and would provide a much longer Rx baseline by the time the knowledge is needed. It would incidentally be much cheaper than learning on the Lunar surface with crew that has a full time work load. I did not suggest delaying potential landings until all the research is in. I suggest that the LEO facility would provide a longer (fleet leader type) baseline of knowledge well before it is needed. Also, the facility could be repurposed for Mars and other gravity levels. It may well be that the health curve for indefinite stay is 0.14 gee, or 0.73 gee. If it is low enough, the centrifuge may be redundant.

    I see the harvesting of ice as being in the nice to have category early with the possibility of it being essential for long term and large scale. I certainly don’t see the proximity of potentially available ice as a reason to lock in location early on. The reasons for being on the moon may call for other locations being more important. I see exploration and general purpose prospecting as being more important early on. The consensus of Earth bound committees that the polar regions are the place to settle could easily be a mistake of assumptions, or not of course. It is important to go get the information early rather than make a mistake that rolls down the years.

    I don’t advocate spending crew training time on Earth guessing at the right moves for dance and gymnastics. I suggest that professionals be sent to get it right. The settlement crew should have a full work schedule that artistic requirements may interfere with. Of course if they choose to get involved in their off time, that’s a bonus.

    If the concern about LOC dominates decisions about crew rotations, then settlement is premature. A year or five delay to gain confidence and iron out problems in the transportation systems would be a good investment compared to transportation being a white knuckle event every time. The Centaur is also a quite expensive stage to work from. It may be the best available, but almost certainly not the best that can become available.

    The hover slam approach that I suggest for some early payloads would be simple acknowledgement that we don’t have all the answers beforehand. Also it would allow much heavier payloads delivered without as many redundant systems. It allows landings without the deep throttling requirements normally called for which eliminates the need for dedicated landing engines. The second stage engine can be refueled in orbit and used for TLI and landings with the technique. This speeds up the development process considerably. A stage that hits a boulder with a landing leg at 5 m/s and tips over at 1/6 gee in vacuum will not lose its’ cargo. It just needs to be able to deploy from other attitudes. This is one of the choke points of a government managed process as opposed to a private results oriented process. By lander 10, they will be nailing it, and without a lander specific development program.

    Depots and rotovators would speed up the process of settlement. The 45 ton LEO payload of New Glen could be 45 tons on the Lunar surface instead of the 5 tons you suggest. The rotovator could be an early deployment not on the critical path as the kinks are worked out. After learning to use it, incoming payloads would provide the energy to return material to TEI. It is simply not used for critical supplies until it is ready. By using it in parallel with settlement until ready, there is no time lost in deploying it. Once the rotovator is fully operational, Mass ratio from LEO to TLI to Lunar surface to TEI becomes about 2.5-3. It would be an incredible waste to not set aside some resources to learn the technique.

    Your scenario is feasible unless it is a government run operation. Even COTS does not get the costs and schedule down where you would like it. As long as you care what the administration thinks, you will be fighting with one or both feet in a bucket. Also, you seem to think everything is sequential, while I see things going in parallel. Deploy the microgravity test facility, depot, and small test rotovator into LEO year one while sending early landers to the Lunar surface. Use the things that work year two to enhance your scenario. By operating seriously instead of politically, all the pieces could be contributing by year four.

  7. peterh says:

    Regarding flat roofs for inflatable habitats covered in loose material, that has the implied assumption that the overburden provides a uniform pressure equal to the internal pressure. In all likelihood, the overburden weight will not be perfectly distributed, and internal pressure will vary to some degree. An inflatable which assumes the overburden weight is less than internal pressure should be far more robust to such variations.

  8. Andrew Swallow says:

    Presidents can plan 8 years a head. NASA can plan for 30 years providing it allows for the regular swap between the Moon and Mars as a destination.

    There will not be a manned Moon Base during Trumps two terms. There may however be a robotic base (or village). During Trump’s first term at least one of the Lunar CATALYST teams should land 30kg-100kg payloads on the Moon. A lander with several tonnes payload may happen in the second term. Development of cargoes for these landers can now start.

  9. DougSpace says:

    Peterh, please look at my page describing the UniHab:

    In it, I clearly state,

    “In fact, air pressure is so great, the UniHab would need indoor tethers to keep the roof relatively flat. This comes to one centimeter diameter Kevlar tethers every 10 feet”.

    And not just tethers but the internal
    walls could hold the roof down.

    So, no, there is no assumption that the weight of the overburden would equal the hab’s air pressure. Otherwise the height of compacted regolith on top would have to be about 11.5 meters which is way more than I want telerobots pushing.

  10. DougSpace says:

    Hi Andrew. I would agree that there likely wouldn’t be a manned lunar base in eight (or actually seven) years from now. But, if my Plan were adopted, here’s what I think could happen by seven years:
    – Announcing of the Plan to open space to development, exploration, and settlement.
    – Identification of the training and talent selection criteria for the long-duration crew. Recurring selection steps to the point of selecting the actual individuals (and dog) who will be moving off Earth to the permanent lunar base. Reports of simulations.
    – Full terminal landing sequence of the full-scale, Masten Terrestrial Demonstrator in 1.5 to 2 years for about $20M.
    – Selection and development of the full-scale lunar lander(s) at the estimated cost of $200 M.
    – Design, development, and testing of the UniHab.
    – Design, development, and testing of telerobots in terrestrial analogue lab environments.
    – Results from the Resource Prospector mission(s).
    – Design, development, testing, and delivery of the UniHab to the lunar surface with the telerobotic coverage with regolith.
    – The first automated landing of the Xeus and the demonstration of full-scale harvesting and processing of ice.

    Although this seems like a lot, no single item would cost more than $200 M in development costs — most a lot less.

    So, whereas seven years may not be enough time to send crew, we would be so far along the path, I think that it would be politically difficult to change directions.

  11. Andrew Swallow says:

    The ” XEUS System Concept Design Reviews” will be out within a couple of years. This will tell us how big a payload it can take. (Xeus Centaur about 5-6 tonnes round trip or Xeus ACES about 25 tonne round trip to spacestation.) Concept design of a cabin for Xeus can then start.

    Ground levelling equipment can be tested.

  12. DougSpace says:

    Hi Andrew. I think that there are some creative ways that Xeus payload can be increased. I believe that Masten’s Xeus Centaur estimate of 16 tonnes to the lunar surface is based upon the assumption of it getting a free ride to TLI upon something like the SLS. I would rather add an external drop tank and get 10 tonnes to the lunar surface using the FH as the launcher or docking a combo of payloads from FH and ULA.

  13. Andrew Swallow says:

    Refuelling depots in LEO and low lunar orbit can make a big difference to the amount of payload delivered by an expendable lander. For a single heavy item multiple launches may be viable. For instance the greenhouse and garage could have their own deliveries.

    The Power and Propulsion Element (PPE) of the Deep Space Gateway is a space tug in disguise. A second one could push things between LEO and lunar orbit.

  14. Andrew Swallow says:

    The dog will cause a few problems. Dogs are meat eaters where as the habitat’s greenhouse can only produce fruit and vegetables. All its food will have to be brought from Earth.

    Dogs need taking for a walk so it will need exercise equipment. Possibly a giant hamster wheel or taking my lead from the Jetsons’s cartoon a treadmill.

  15. DougSpace says:

    Thanks for your comments Andrew. I appreciate your bringing up the dog. It is questions like that which help me focus on areas to work on to improve the Plan for Sustainable Space Development. Someone within the Space Development Network will need to write up a page specifically addressing this issue.

    With a bit of research, I have found that dogs are actually omnivorous rather than strictly carnivorous. I suppose that I already knew this because, as a kid, when we had dogs, I saw them eat all sorts of stuff that wasn’t meat. I am also aware that, to keep the price down, manufactures of dog food typically include a lot of lower-cost plant-based material in dog food.

    For vegan pet owners, there’s several companies that sell nutritionally-designed dog food that contains no meat. There are certain nutritional elements that have to be addressed to ensure that dogs are getting what they need. Being a (lacto-ovo) vegetarian-since-birth physician myself, I am familiar with the special nutritional considerations for vegans and they are easily met. Dogs are a more challenging because they are more carnivorous than humans.

    But as I research into it, there seems to be a path to feeding a do based upon plantsg. There are examples of vegan dogs including one that had the record for longevity:

    However, the plan for the UniHab would include a tilapia fish tank fed on spirulina grown in drapes and using the appropriate LEDs:

    The fish would need to be deboned and baked before being mixed into the plant-based recipe for the dog meal. Eggs are also especially good for dogs although this involves having to deal with the raising of other animals with their own considerations. I do anticipate a dedicated farm module in the phase after the Initial Crew Phase.

    I think that dog nutrition experts could come up with a recipe that would likely work over the long run. Also, the size of dog might be a consideration to reduce the amount of time the crew would spend making dog food.

    Are there any other aspects of the Plan which anyone would like to comment on pro or con?

  16. Paul451 says:


    “there is no assumption that the weight of the overburden would equal the hab’s air pressure. Otherwise the height of compacted regolith on top would have to be about 11.5 meters”

    Que? What density are you assuming for regolith? Under lunar gravity, countering air-pressure by mass alone would take 60 tonnes/m². 11.5m assumes a density over 5t/m³, twice as high as solid concrete or granite.

    Re: The dog. (Laika if it’s a girl, Rover if it’s a boy.)

    Actually dogs take quite well to human-standard treadmills. (They seem to enjoy it, once they get used to the movement. Even manual (non-electric) treadmills.) The 1/6th G might be an issue. Elastic tethers work well for bipeds, quadrupeds seem like a bigger problem. But Doug’s proposal has a centrifuge anyway, logically you would use that for exercise. Plus if you put a banked track around the hab’s rim, people (and dogs) can create their own “centrifuge” while running.


  17. DougSpace says:


    Here’s my calcs:
    – 1/2 atm is about 5 tonnes/m2.
    – Compacted regolith is about to 2.6 g/cc = 2.6 tonne/m2.
    – So, it would take 1.92 meters thick to exert 5 tonnes/m2 down in a 1 gee environment.
    – But, lunar gravity is 1/6 gee.
    – So, 1.92 X 6 = 11.5 meters thick.

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